What lifespan setting do you play on and why?

I like long because I can take my time with most of my Sims and they can have some fun instead of grinding for skills or promotions. I will age up my Sims when I feel they're ready though -- with child Sims it's usually when they''ve finished two of the child aspirations, with teens it's when they've either finished an aspiration or they've reached a point where they have to be an adult to continue to progress (though I try to pick a first aspiration that doesn't require adulthood). If they have a group of friends, I invite them over so they can all age up at the same time so they have friends as they age up. YAs I age up to Adult when they finish their first career. and to Elder when they complete their second at which time I move them out and take them off the Played Households so they can die (since my played households don't age unless I actively play them). I'll go with aging off when new content has been announced that I want my current Sims to enjoy, for example when Seasons was announced before it launched.

I'm working on a template save with a lot of new and remodeled houses, that I plan to use for one-off saves; I do want to try both short and normal lifespans just to see how they work for me and my gameplay.